Question

In a circuit with a battery and a switch that has several light bulbs wired in series, which will be the effect of adding another light bulb to the circuit?

Select one:

a. Nothing will change

b. The new bulb may not light up

c. The lights will all shine less brightly than before

d. The lights will all shine more brightly than before

Answer 1

Bulb is like resistance, and if we change voltage across resistance then current will changed and vice versa, but one thing is always constant that is it's resistance so to find power we will use formula P = V​​​​​​2/R, here R is constant and by changing voltage, power will be changed.

Now according to question if we increase number of bulbs in series then voltage will be divided across each bulb or resistance because total voltage drop across battery will have to be remain same, so from the above formula power will be decreased as voltage decreases by increasing number of bulbs in series so power will also decreased and when power is decreased of bulb then it's brightness also decreased.

option c, The lights will all shine less brightly than before.

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